I read (actually listened to the audiobook of) Ready Player One about two years ago and couldn't get into it, so DNF. Now that so many people talk about how great it is and the movie has come out, I'm going to revisit it, ebook this time so maybe eyes can get into what ears couldn't.
I think streamlining is critical to movie adaptions. See how many subplots and details they've taken out of the Harry Potter books? Still, the worst streamlining I've seen is perhaps Ender's Game. The book is 324 pages according to Wikipedia, and there are shiploads of "tell, not show" and so it can be 900 pages if more "show, don't tell" was done. The movie, IMHO, kept too many nonessential details and didn't have enough of what makes the book great.